A bicycle can run through a smaller force once running out under a condition that wheels are rotated by a human force, but will be applied by an extra-large repulsive force while beginning to pedal for starting, accelerating, climbing and the like, and part of input energy as impact recoils to knees, ankle joints, waist and the like, so a heavy load is generated on a human body and the input energy cannot be efficiently utilized, thereby reducing a propulsion force. Then, particularly in case of fast start, fast acceleration, climbing, heavy body weight of a bicyclist or heavy weight of loaded cargoes and the like, the load (resistance) of the human body is increased, and correspondingly the needed energy is increased.
An up-and-down motion of feet is converted into a rotation motion through a crank in the case of the bicycle, so a burden to the knees and the ankle joint is increased because a foot force is difficult to be smoothly transmitted at a top dead center and a bottom dead center particularly, and interruption of a torque and reduction of velocity may be caused. Problems that stall is easily caused and running stability is reduced exist in case of low-speed running.
Therefore, in the past, various structures were researched with respect to a purpose of alleviating fatigue of the bicyclist by absorbing impact during running, attempting to increase rotation efficiency and stabilizing the propulsion force and acceleration.
For example, in a patent literature 1, the following content is disclosed: “a bicycle includes an automatic telescopic change type crank mechanism, and has a small pedal rotating radius in a cruise running mode, and when the bicycle enters a running mode in which a heavier burden is applied, the pedal rotating radius is automatically elongated according to the resistance to obtain a great rotation torque”.
In a patent literature 2, the following content is disclosed: “a shock absorber for a bicycle includes a first member, a second member and a first elastic member, wherein the first member can be fixed to a first frame member and includes a containing space formed inside and at least one first protrusion part protruding from an inner circumferential surface of the containing space to the inner side; the second member can be fixed to a second frame member, configured in the containing space of the first member in a relatively rotation manner and includes a second protrusion part protruding from an outer circumferential surface to the outer side; and the first elastic member is assembled and connected to one of two spaces partitioned by the two protrusion parts between the first member and the second member, retained on the first protrusion part and the second protrusion part and separated from at least one of the inner circumferential surface and the outer circumferential surface at an interval, and extended and retracted by virtue of relative rotation of the two members”.
In a patent literature 3, the following content is disclosed: “a driving gear for a bicycle includes a gear body and a supporting body, wherein the gear body includes a plurality of teeth at the periphery; the supporting body supports the gear body; a power transmitting part for transmitting power from one of the gear body and the supporting body to the other is arranged between the gear body and the supporting body; a gap through which the gear body and the supporting body can relatively rotate by a specified angle is formed at the power transmitting part; and elastic bodies are arranged at different parts of the power transmitting part. The gap is remained due to the elastic bodies, and elastic deformation is generated to absorb the gap when the gear body and the supporting body relatively rotate, so that power transmission from the power transmitting part is possible.”
In a patent literature 4, the following content is disclosed: “a power transmitting apparatus for a bicycle has a composition that: a spiral spring wound and assembled towards an opposite direction of a rotation direction of a front gear is arranged in an inner circumferential wall of the front gear, and due to an effect of the spiral spring, a torque generated by an excessive pedaling pressure of a pedal arm is accumulated on the spiral spring, and the accumulated torque is supplemented when pedal input is insufficient, thereby improving rotation efficiency of the pedal.”
In a patent literature 5, the following content is disclosed: “a crank apparatus for a bicycle is characterized in that metal parts of a plurality of spring supporting sheets are radially embedded into a gear shaft of the bicycle in a protruding manner, annular bodies of which inner circumferential surfaces are supported and are rotated concentrically with the gear shaft are embedded into outer circumferential edges of the spring supporting sheets to serve as a base part of the crank, spring pressing sheets are arranged on the inner circumferential surfaces of the annular bodies in a manner of corresponding to the spring supporting sheets in a protruding manner, and spring bodies are inserted between the spring supporting sheets and the spring pressing sheets. Thus, when the crank is stressed to rotate, the annular bodies at the base part are rotated together earlier than the gear shaft, the spring bodies are compressed by the protruded spring pressing sheets, and the spring supporting sheets are pressed by a reaction force to enable the gear shaft to rotate”.
However, an existing art above has the following problems:
(1) For the bicycle in the patent literature 1, the pedal rotating radius is automatically elongated according to the resistance, so the following problems exist: a structure of the crank mechanism becomes complicated, the quantity of parts is increased, and action stability, assembly operability and mass production are poor.
In addition, the following problems exist: the pedal rotating radius is increased at a large resistance, so high output can be obtained through low input, and the load during start of pedaling and the like can be reduced; however, a track of the pedal cannot form a circular track, and a reluctant pedaling manner is needed; and therefore, a great burden is generated to the knees, ankle joint and the like.
(2) For the shock absorber for the bicycle in the patent literature 2, when impact acts on the first frame member or the second frame member from a pavement, the first member and the second member are rotated, the first elastic member assembled and connected in one of the spaces partitioned by the two protrusion parts is clamped by the two protrusion parts to compress and deform, and an elastic restoration force is generated to absorb the impact. However, a suspension assembly body is fixed to a main frame member through an outside member, so impact energy at an initial motion of the crank is absorbed and accumulated, the accumulated energy cannot be converted into a rotating force to serve as the propulsion force to be effectively utilized when the elastic body is restored, and improvement of the rotation efficiency and acceleration, homogenization of the rotation torque and the like are not considered.
(3) A purpose of the driving gear for the bicycle in the patent literature 3 is to relieve impact generated by a driving force when pedaling starts, and the driving gear has a structure that the elastic body is arranged between the gear body and the supporting body at a part different from the power transmitting part and generates deformation in a torsion manner, so the following problems exist: the elastic body is difficult to deform and difficult to accumulate energy, so the restoration of the elastic body is difficult to be effectively converted into the rotating force, and effective utilization of the energy is poor.
In addition, the number of the parts is large, the structure is complicated, the mass production is poor. Moreover, the gear body and the supporting body are integrated by the elastic body, so the following problems exist: the gear body and the elastic body are difficult to be replaced, and maintainability is poor.
(4) A purpose of the power transmitting apparatus for the bicycle in the patent literature 4 is to accumulate the torque generated by the excessive pedaling pressure of the pedal. The accumulated torque is supplemented when the pedal input is insufficient, so that the input of pedaling pressure is stabilized to strive to improve the rotation efficiency of the pedal, and the propulsion and acceleration are stabilized to alleviate the fatigue. However, accumulation and supplement of the torque are performed by a clockwork (plate spring)-shaped spring, a coiled spring and other spiral springs, so the following problems exist: time is spent before the spiral spring is completely wound to accumulate the torque, and during the period, the pedal shaft idles relative to the front gear, the power cannot be transmitted, and usability is obviously poor.
In addition, the following problems exist: the power cannot be transmitted from the pedal shaft to the front gear under a condition that the spiral spring is damaged, and the bicycle cannot run, so power transmission reliability and stability are poor.
(5) For the crank apparatus for the bicycle in the patent literature 5, the inner circumferential surfaces of the annular bodies serving as the base part of the crank are supported on the outer circumferential edges of the spring supporting sheets, the following problems exist: the crank and the gear shaft are easy to rotate together due to a friction force between the inner circumferential surfaces of the annular bodies and the outer circumferential edges of the spring supporting sheets, the annular bodies are difficult to rotate earlier than the gear shaft, the spring body cannot be reliably compressed, the action stability is poor, force accumulation (absorption of the impact energy) at the top dead center and restoration at the bottom dead center cannot be fully performed, and effects of improving the rotation efficiency and acceleration and homogenizing the rotation torque are insufficient.
In addition, the crank apparatus must be assembled at two ends of the gear shaft, so the following problems exist: the quantity of the parts is increased, the whole apparatus is complicated, large and poor in space conservation and mass production, and since torsion of the gear shaft is generated due to phases of the cranks at the two ends; accumulation of the input energy and conversion from the accumulated energy to the rotating force cannot be efficiently performed, and durability, action stability and efficiency are poor.
Therefore, in order to solve the existing problems above, the inventor provides a bicycle as follows: a rotational apparatus for a bicycle is assembled on a rotating shaft of the bicycle of which wheels rotate and run through a human force. Thus, the impact energy or extra-large input energy generated by a heavy load and the like applied from outside can be reliably absorbed and accumulated in initial motions such as starting, accelerating, climbing and the like or during running, thereby greatly reducing the human load. Moreover, the accumulated energy is effectively utilized in rotation of the rotating shaft losslessly when the input energy is reduced or interrupted; rotation transmitting reliability and efficiency are excellent; lightweight, easiness in disassembly and assembly and excellent maintainability and productivity can be achieved by virtue of a simple structure with fewer parts; the rotational apparatus can be simply and conveniently assembled into an existing bicycle; and the mass production, assembly operability, space conservation and universality are excellent. The bicycle includes the rotational apparatus for the bicycle, so that a load applied to the waist, legs and the like of a user can be reduced, the acceleration, uniformity of the rotation torque and stability during low-speed running are excellent when heavy cargoes are transported or a person with heavy body weight is carried, a load applied to the knees, the ankle joint and the like of a bicyclist can be reduced without any complicated operation, and the bicycle can be easily ridden by women, the old, housewives carrying heavy cargoes or children, can serve as a daily necessity which can easily run on ramp or a road with a large resistance, is excellent in the acceleration, uniformity of the rotation torque and stability during low-speed running, can also be used for rehabilitation training or athletic competition and has excellent action stability, operability and universality. Moreover, the inventor proposes a bicycle with the following structure based on a purpose of providing the bicycle above (a patent literature 6).
Namely, in the patent literature 6, the following content is disclosed: “a bicycle includes: a rotational apparatus for a bicycle, a left and a right crank arms and a pedal, wherein the rotational apparatus includes an internal rotation member and an external rotation member; the internal rotation member includes a rotating shaft; the external rotation member is configured on the rotating shaft of the internal rotation member in a rotation manner; the left and the right crank arms are assembled at two ends of the internal rotation member of the rotational apparatus for the bicycle at a phase difference of 180°; and the pedal is configured at the end parts of the crank arms in a rotation manner. In the bicycle:
The internal rotation member includes more than one outer circumferential protrusion part integrally formed with the rotating shaft or fixedly arranged at the outer circumference of the rotating shaft and protruding towards the outer circumferential side of the rotating shaft.
The external rotation member includes a side plate part, inserted into the rotating shaft in a rotation manner at a side part of the outer circumferential protrusion part of the internal rotation member; an outer cylinder part, uprightly arranged at the outer circumference of the side plate part concentrically with the rotating shaft on an outer side of the outer circumferential protrusion part of the internal rotation member; and more than one inner circumferential protrusion part, integrally formed with the side plate part and/or the outer cylinder part or fixed to the side plate part and/or the outer cylinder part in a manner of protruding to an inner circumference side of the outer cylinder part and configured alternately with the outer circumferential protrusion part of the internal rotation member.
A chain ring is arranged in a proper shape or fixedly arranged on the side plate part or the outer cylinder part of the external rotation member.
An elastic part is assembled between the outer circumferential protrusion part and the inner circumferential protrusion part on a rotation direction side of the advancing outer circumferential protrusion part, and when the internal rotation member and the external rotation member are rotated, the elastic part is clamped between the outer circumferential protrusion part and the inner circumferential protrusion part and generates elastic deformation.